High speed scanning slot antenna fed by variable delay waveguide having hinged oscillated vane



1964 R. G. SHANKWEILER ETAL ,744 HIGH SPEED SCANNING SLOT ANTENNA F EDBY VARIABLE DELAY I WAVEGUIDE HAVING HINGED OSCILLATED VANE Filed June30, 1960 22 2 I0 a2 l4 FEED L LOAD SCAN ANGLE 6 l I I -90 0 +90 VANEANGLE(DEV|AT!ON FROM VERTICAL) RAY G. SHANKWEILER RICHARD J. KLENS ATTONEY s United States Patent HIGH srnnn scANNrNd sLoT ANTENNA FEB BYVARIABLE DELAY WAVEGUHDE HAVTNG HEPJGED OSCILLA'I'ED VANE Ray G.Shanltweiier, Cranhury, and Richard E. Klensch, Trenton, NJ assignors tothe United States of America as represented by the ccretary of the AirForce Filed June 3t), 1960, Ser. No. 46,124 2 Claims. (-21. 343768) Theinvention relates to a hinge antenna for high speed scanning which iscompact enough for incorporation in the wing of an aircraft.

Angular scan is accomplished in an antenna array by changing therelative phase between the radiating elements of the array. In awaveguide antenna array the procedure that is used to change the phasedifference between adjacent elements is to change the phase velocity ofthe wave inside the guide. There are several ways that this can be done:first, changing the operating frequency or frequency scan; second,changing the permeability of the interior, for example, filling thewaveguide with ferrite and varying the magnetic field; third, changingthe field strength of the wave, and fourth, changing the waveguidegeometry or mechanical scan. The present invention concerns an improvedmechanical scan structure.

The prior art structure for obtaining high speed scanning of an antennaby mechanical means involves the movement of the entire back side of thewaveguide that is opposite the aperture. This structure has numerousdisadvantages, the principal ones being that a large mass must he movedand the waveguide structure is made weaker by having two longitudinalcuts made the length of the array.

It is thus an object of this invention to provide a hinge antenna. forhigh speed scanning which has high resolution and is simple inconstruction.

It is a further object of this invention to provide an improved meansfor varying the waveguide geometry of an antenna for obtaining highspeed scanning.

It is a still further object of this invention to provide a hingeantenna for high speed scanning which includes a waveguide having feedand load ends, an elongated aperture in one side of the waveguide, and avane pivotally mounted within the waveguide extending along the lengthof the aperture and spaced therefrom.

The nature of the invention, further objects and advantages will appearmore fully on consideration of the embodiments illustrated in theaccompanying drawings.

In the drawings:

FIG. 1 is an illustration of the end view of one embodiment of theinvention taken along 2-2 of FIG. 2;

FIG. 2 is an illustration of the top view of the BIG. 1 embodiment andincludes the typical pattern for the antenna;

FLIG- 3 is a perspective view of the waveguide portion of the novelantenna minus the vane element; and

FIG. 4 is a graphical representation of the effect that the vane anglemakes on the antenna scan angle.

Referring now more particularly to FIGS. 1, 2 and 3, a hollow waveguideof square cross-section has a feed end 12 and a load end 14. Anelongated aperture 16 adapted to radiate extends lengthwise along oneside of the waveguide 10. The waveguide has a suitable inner diameter topermit propagation of the TM mode. Metallic extensions 18 and 20 oflength slightly longer than aperture 16 are bonded to the side of thewave- 33,122,744 Patented Feb. 25, 1964 guide containing the aperture toform a ground plane 22 on the aperture side of the waveguide. High speedscanning is accomplished by a drive means 24 driving a vane 26 back andforth within the waveguide between the extremes A and B. The vane 26 ispivotally connected to the waveguide by means of a piano hinge means 30.

The specific structure of drive means could be various types; however,it has been known that connecting the upper portion of the vane 26 to amotor-driven cam actuated push rod provides an excellent drive. The camis shaped to produce a saw-tooth type scan.

Energy is propagated through the waveguide 10 from the feed end 12toward the vane 26. When the vane is vertical in position C, the phasevelocity is maximum (for a symmetrical field within the waveguide) andfor a continuous radiator a beam near broadside would be expected. Thepresence of the aperture 16 on one side of the waveguide no longer keepsthe field inside the waveguide symmetrical about the center of theguide. For this reason, maximum phase velocity occurs when the vane 26is in the B position and the minimum phase velocity occurs when the vane26 is in the A position.

FIG. 4 illustrates the deviation from the symmetrical field case thatthe novel antenna takes in the relationship of the vane position to thescan angle 9 of beam 32. The solid curve represents the symmetricalfield case. The dashed curve represents the experimental findings fromthe testing of a model of the novel antenna. The model was constructedof 1.4 inch square waveguide with a pivotal vane of A inch aluminumsheet inserted 1 inch into the waveguide and a 38 inch aperture length.The included angle between positions A and B was 60. This continuousslot traveling wave antenna was excited in the EM mode and operated at afrequency of 9.1 kmc. With the vane in position A, the beam 32 was at anangle of 32 from broadside. in position B, the beam 32 was 12 frombroadside. l

Although but a single embodiment of the invention has been shown anddescribed, it will be apparent to those skilled in the art that manyother forms thereof, as well as changes in that described, are possible.Having thus described the invention as a particularly simple system forhigh speed scanning, we claim:

1. A hinge antenna for high speed scanning, said antenna comprising: awaveguide having feed and load ends, and an elongated aperture in oneside of said waveguide; an elongated vane; piano hinge means attached tosaid waveguide and said vane for pivotally mounting said vane withinsaid waveguide extending along the length of said aperture; and meansfor driving said vane hack and forth to produce said scanning.

2.v A hinge antenna for high speed scanning, said antenna comprising: awaveguide of square cross-section having feed and load ends, and anelongated aperture adapted to radiate in one side of said Waveguide;metallic extensions bonded to the said side of the waveguide containingthe aperture forming a ground plane on the aperture side of the saidwaveguide; an elongated vane; piano hinge means attached to saidwaveguide and said vane for pivotally mounting said vane within saidwaveguide extending along the length of said aperture; and means fordriving said vane back and forth to produce said scanning.

References Cited in the file of this patent UNITED STATES PATENTS2,602,893 Ratliff July 8, 1952

1. A HINGE ANTENNA FOR HIGH SPEED SCANNING, SAID ANTENNA COMPRISING: AWAVEGUIDE HAVING FEED AND LOAD ENDS, AND AN ELONGATED APERTURE IN ONESIDE OF SAID WAVEGUIDE; AN ELONGATED VANE; PIANO HINGE MEANS ATTACHED TOSAID WAVEGUIDE AND SAID VANE FOR PIVOTALLY MOUNTING SAID VANE WITHINSAID WAVEGUIDE EXTENDING ALONG THE LENGTH OF SAID APERTURE; AND MEANSFOR DRIVING SAID VANE BACK AND FORTH TO PRODUCE SAID SCANNING.